This invention relates generally to an apparatus for guiding the movement of a power cutting tool relative to a workpiece and more specifically to an apparatus which facilitates formation in a workpiece of arcuate cuts, rectilinear cuts, or a series of parallel, regularly-spaced, angled cuts.
A router is a commonly available piece of power equipment which is used for cutting precise edges and grooves in a workpiece. Although there are guide mechanisms known in the prior art which permit a straight cut or groove to be made in a workpiece, problems arise when one is faced with the task of making a plurality of identical grooves in parallel along the length of the workpiece, an array of identically positioned grooves in a sequence of workpieces, or arcuate cuts. In a typical straight line cutting guide, the workpiece is clamped securely to the guide and the required cut is made. In order to make additional cuts parallel to the first, the workpiece must be loosened within the guide for each cut and be manually measured, marked and repositioned, in order to line up properly with the preceding cut. This procedure is time consuming and subject to operator error as each cut is essentially a distinct operation, and the opportunity exists for a cumulative error to be introduced, which results in nonparallel or irregular spacing.
Conventional guides for making angular cuts in a workpiece usually are limited as to the range of angles relative to the edge of the workpiece which can be achieved. Typically a range of only 90 degrees, or 45 degrees on either side of the perpendicular, is standard. Thus, if grooves must be cut at very acute angles to the edge of the workpiece, oftentimes the guide may be of no use. Typical examples of applications in which a set of evenly spaced, accurately cut parallel grooves are required is in the fabrication of louvered doors, crib gates, or other pieces of woodwork which have evenly spaced slats or rails. The precision of the spacing and the parallelism of the grooves have a pronounced effect on the aesthetics of the finished product, and the conventional method of continually repositioning the workpiece within the guide is counterproductive to the required precision. In the case of louvered doors where two oppositely facing support pieces have corresponding sets of equally spaced grooves, misalignment may mean that insertion of the slats in the opposing support pieces may become impossible.
U.S. Pat. Nos. 3,741,063 to Bretthauer, 4,109,091 to Akin, 4,050,340 to Flanders, and 2,825,370 to Fieber are examples of previously known guides which permit single angular cuts to be made in a workpiece. However, none provide for controlled movement of the workpiece relative to the guide so as to create a series of such cuts in parallel fashion. Also, each discloses less than 360.degree. accessibility to the workpiece.
U.S. Pat. No. 4,023,273 to Treleaven does teach a device for making circular cuts, but it requires establishment of a pivot point in the workpiece itself. This means that if only a circular groove were to be made, the workpiece would remain marred by a hole at the center of the groove. Also, the circle is limited to a minimum diameter.
Therefore it is an object of the present invention to adapt a cutting tool to make precise rectilinear or arcuate cuts within a workpiece at any orientation relative to the workpiece and to do so in a simple, efficient, and reliable manner. Another object is to provide a guide which allows a cutting tool to produce accurately a series of parallel, regularly-spaced grooves or cuts within a workpiece or a succesion of workpieces in a repeatable manner. Another object is to provide apparatus for guiding multiple rectilinear and parallel cuts in a workpiece which can be adapted easily to a variety of power cutting tools including routers and saber saws. Another object is to provide a guide apparatus for guiding multiple, regularly spaced arcuate cuts and for cutting circles. Yet another object is to provide a means for making circular cuts or grooves in a workpiece in a continuous fashion, without repositioning or marring the workpiece.